1. Field of the Invention
This invention relates to hinges for sectional doors and, more particularly, to a novel, low-profile hinge constructed around a smaller diameter hinge pin fabricated from a spring steel to thereby significantly reduce the gap between door sections to preclude the insertion of a fingertip into the gap.
2. The Prior Art
Sectional doors, as the name implies, are fabricated from discrete door sections that are hingedly joined along adjacent edges to create the sectional door. Sectional doors are specifically designed to provide a closure mechanism across a large opening, typically, an automobile garage, or the like. As such, a sectional door spans a relatively wide opening, usually several meters in width and, on occasion, several meters in height. The sectional door is fabricated from a plurality of door sections hingedly joined in an edge-to-edge relationship to enable the sectional door to travel up and down between its vertical orientation where it serves as the closure to the opening and the open position where it is supported in an overhead orientation where it is temporarily held until returned to the closed or vertical position. The ends of the door sections are supported and guided by rollers that are confined to tracks. The tracks are positioned adjacent the opening such that they support the sectional door in its closed position, its opened position, and during its traverse between these two positions. The tracks include a curved section across which the sectional door traverses between positions. Traversal of this curved section of track is the reason the sectional door is assembled from door sections hingedly joined together along adjoining edges. It is this feature of the sectional door that creates a particularly dangerous situation. Specifically, as the sectional door is lowered, and each door section traverses the curved section of track, each door section changes its planar orientation from the horizontal to a vertical position. The hinges between door sections accommodate this change in orientation so that the entire sectional door is able to effectively follow a curvilinear path in its movement to the closed position. Customarily, this entire procedure of closing a sectional door by lowering it from its elevated, horizontal, open position to its lowered, vertical, closed position requires less than about eight seconds. This means that as each door section traverses the curved section of track it relatively rapidly rotates through about a 90 degree orientation from the horizontal to the vertical positions. As each door section makes this transition in orientation, the hinges between door sections cause a gap to be created between door sections. This gap opens and closes relatively rapidly due to the overall closure rate of the sectional door.
Historically, the door sections were hingedly joined in their edge-to-edge relationship by door hinges specifically designed for use on sectional doors. These sectional door hinges were configured as dual purpose hinges in that those door hinges mounted along the outer edges of the sectional door could serve double duty not only as a hinge but also as the support socket for the shank of a roller bearing engaged in the adjacent support track. To accomplish this double duty the door hinge was fabricated around a tubular socket which served both as the pivot around which the hinge pivoted, and also as a socket to telescopically receive the shank of the roller bearing. As a natural consequence of using the tubular socket as the hinge pin, the door hinge was fabricated such that the tubular socket was supported several centimeters away from the surface of the sectional door. In turn, this rather large spatial distance between the pivot of the door hinge and the surface of the sectional door resulted in the prior art door hinge creating a relatively large gap between door sections as the sectional door moved downwardly across the curved section of track. This gap was generally within the range of at least two to three centimeters, a gap capable of receiving the fingers of most people.
The foregoing hinge configuration has resulted in the severe injury to the fingers of literally thousands of people. These injuries occur when the person operating the sectional door either inadvertently or deliberately places his/her fingers in the gap between door sections as the sectional door is being lowered to the closed position. Often, these injuries occur when the person grasps the sectional door to hasten its closure. Regrettably, the logical place to grasp a sectional door, particularly one that is insulated and thereby has a smooth inner surface, is at the edge of the door section, the edge having been exposed by the pivotal movement of the sectional door as discussed hereinbefore.
As a consequence of these injuries, the trend in the garage door or, rather, sectional door industry has been to change the old style sectional door hinge to a flatter, conventional leaf-type or strap hinge. This hinge, as the name implies, uses two, essentially flat, hinge leaves or hinge plates pivotally joined at their center around a hinge pin. This type of hinge is fabricated by at least two interdigitated fingers which are curled about a common hinge pin.
In recognition of the fact that the spatial separation of the centerline of the hinge pivot from the surface of the sectional door determines the extent to which the gap between door sections will open as the door sections pivot about the hinges, every possible step has been taken to reduce this spatial separation. However, it has been found that there is a minimal distance by which the pivot point can be brought simply due to the nature of the material of construction of the hinge itself. Simply stated, the forces imposed on the hinges dictate that the metal from which the hinge is constructed must be of sufficient thickness to withstand the forces involved. For example, I have found that a hinge capable of withstanding the normal forces imposed by movement of the sectional door must be fabricated from a galvanized steel having a gauge thickness of at least 14 gauge. Further, and even more importantly, the hinge pin must be fabricated with a diameter of at least 3/16 of an inch (0.476 cm) in order to withstand the forces imposed upon the hinge. For example, I have found that a strap hinge fabricated from a 14 gauge, galvanized steel and having a 3/16 inch (0.476 cm) diameter hinge pin can withstand a pull force of about 450 pounds (204 kilograms) before deformation of the hinge occurs. This deformation causes the hinge pin to bend and the enclosing pin tube to stretch and open. Even at 3/16 inch (0.476 cm) diameter, this hinge pin creates a gap of at least 5/8 inch (1.5875 cm) between door sections. This gap is clearly large enough to receive at least the tips of the fingers of most people.
In an attempt to reduce this gap to a maximum of only 1/4 inch (0.635 cm), I ordered the fabrication of a strap hinge with a hinge pin having a 1/8 inch (0.318 cm) diameter. Regrettably, this hinge failed at a pull force of only about 200 pounds (91 kilograms), a strength utterly inadequate for most sectional door applications.
In view of the foregoing, it would be an advancement in the art to provide a strap hinge fabricated around a smaller diameter hinge pin to provide for a reduced gap opening in a sectional door while at the same time maintaining the same or greater strength characteristics of a hinge pin of a larger diameter. It would be an even further advancement in the art to provide a hinge pin fabricated from a material of construction that has historically not been considered as a suitable material of construction for a hinge pin. It would be an even further advancement in the art to provide modifications in the manufacture of strap hinges in order to accommodate this new material of construction for hinge pins. Such a novel invention is disclosed and claimed herein.